Van Spitzenbergen Beatriz Akemi Kondo, Andrade Gabriela Bohnen, Dias Erika Sousa, Alegre Júlia Bacarin Monte, Dias Gabriela Ferreira, Grobe Nadja, Moreno-Amaral Andrea Novais, Kotanko Peter
Department of Postgraduate Program in Health Sciences, Research Laboratory of Anemia and Immunology (LabAIRe), Pontifícia Universidade Católica do Paraná, Curitiba, PR, Brazil.
Renal Research Institute, New York, NY, USA.
Nephrol Dial Transplant. 2025 Jun 30;40(7):1342-1349. doi: 10.1093/ndt/gfae275.
In patients with advanced CKD the lifespan of red blood cells (RBCs) is often shortened, a condition attributed to the 'uremic milieu.' We reported recently that the uremic solute 3-carboxy-4-methyl-5-propyl-2-furanpropionate (CMPF) shares structural similarities with Jedi1, a chemical activator of the mechanosensitive cation channel PIEZO1, whose activation increases calcium influx into cells. Against this backdrop, we hypothesized that CMPF may induce premature RBC death (eryptosis) through prolonged CMPF-induced activation of PIEZO1 located on RBCs. To test this hypothesis, we explored if CMPF, at concentrations found in uremia, interacts with PIEZO1 located on RBCs, increases intracellular calcium (icCa2+), and induces eryptosis.
RBCs from healthy individuals were incubated with CMPF or Jedi1 (both at a concentration of 87 µM), in the presence or absence of the PIEZO1 inhibitor GsMTx-4 (2 µM). We challenged RBCs osmotically through incubation in solutions of NaCl at concentrations between 3.0 and 9.0 g/L and determined their osmotic fragility. Using flow cytometry, we quantified in incubated RBCs icCa2+ levels and phosphatidylserine exposure, a cellular marker of eryptosis.
Incubation of RBCs with CMPF and Jedi1 significantly increased RBC osmotic fragility, an effect prevented by GsMTx-4. At 6.0 g/L NaCl, incubation with CMPF and Jedi1 increased exposure of phosphatidylserine and elevated icCa2+ levels of RBCs, indicating increased eryptosis. Notably, at an isotonic NaCl concentration of 9.0 g/L, CMPF-but not Jedi1-significantly increased RBC phosphatidylserine exposure and icCa2+ levels; both effects were diminished by GsMTx-4.
Our findings support the hypothesis that CMPF may function as an endogenous activator of PIEZO1, increase icCa2+ levels, trigger eryptosis, and, through this pathway, possibly shorten the RBC lifespan. To what extent these in vitro findings are operative in advanced CKD warrants clinical studies.
在晚期慢性肾脏病患者中，红细胞（RBC）寿命常缩短，这种情况归因于“尿毒症环境”。我们最近报道，尿毒症溶质3-羧基-4-甲基-5-丙基-2-呋喃丙酸（CMPF）与机械敏感阳离子通道PIEZO1的化学激活剂Jedi1结构相似，PIEZO1激活会增加钙流入细胞。在此背景下，我们推测CMPF可能通过长期激活RBC上的PIEZO1诱导红细胞过早死亡（红细胞凋亡）。为验证这一假设，我们探究了尿毒症浓度下的CMPF是否与RBC上的PIEZO1相互作用、增加细胞内钙（icCa2+）并诱导红细胞凋亡。
将健康个体的RBC与CMPF或Jedi1（浓度均为87µM）一起孵育，同时存在或不存在PIEZO1抑制剂GsMTx-4（2µM）。通过在3.0至9.0g/L浓度的NaCl溶液中孵育对RBC进行渗透压挑战，并测定其渗透脆性。使用流式细胞术，我们量化了孵育的RBC中icCa2+水平和磷脂酰丝氨酸暴露情况，磷脂酰丝氨酸暴露是红细胞凋亡的细胞标志物。
用CMPF和Jedi1孵育RBC显著增加了RBC渗透脆性，GsMTx-4可阻止这种作用。在6.0g/L NaCl条件下，用CMPF和Jedi1孵育增加了磷脂酰丝氨酸暴露并提高了RBC的icCa2+水平，表明红细胞凋亡增加。值得注意的是，在等渗NaCl浓度为9.0g/L时，CMPF而非Jedi1显著增加了RBC磷脂酰丝氨酸暴露和icCa2+水平；这两种作用均被GsMTx-4减弱。
我们的研究结果支持以下假设：CMPF可能作为PIEZO1的内源性激活剂发挥作用，增加icCa2+水平，触发红细胞凋亡，并通过该途径可能缩短RBC寿命。这些体外研究结果在晚期慢性肾脏病中的实际作用程度有待临床研究验证。
